How to import fbx image to an existing project
This is two questions, but I will answer both.
First, your description sounded like you are thinking of the tire as a 2D rendering of a 3D object, being moved about in a 2D space. It is in a 3D space. If you already understood that, I am sorry. But anyway, to fake it and make the tire render in front of everything all the time even if it is positionally behind it, you can use the render engine specific solution, or a permanent one that works with all engines. I will describe the latter.

Place the tire in its own collection, and place everything else except the lights and camera in their own collection together.
Create a new View Layer.
In that new layer, uncheck the collection without the tire.
If you do not want the tire to cast shadows on anything, uncheck its collection from the first view layer.
In Properties editor -&gt; Rendering tab -&gt; Film panel, enable Transparent.
In the Compositing screen, enable Use Nodes, then add both view layers, and use Alpha Over to put the tire over the other view layer.

About the rotation transform question, look at the top of the 3D view for a magnet icon. Check that the setting next to it is “Increment” and not something like “Vertex,” and enable Rotation and Scale (Location is enabled by default). Then, click the magnet to turn on snapping. Rotation will now snap to 5 degree increments.